Double patterning with 193nm immersion lithography becomes to most promising candidate for 32nm half pitch node
and possibly below 32nm half pitch. Several double patterning methods have been suggested such as LELE (Litho-Etch
-Litho-Etch), LLE (Litho-Litho-Etch) and Spacer defined process, however, LLE process is pointed out as low cost
double patterning technique because of its simplicity. But LLE process needs new method to maintain 1st lithography
pattern and additional freezing processes have been suggested
In SPIE Advanced Lithography 2009, freezing free "Posi/Posi" process was introduced as candidate for LLE process.
This is LLE process that uses two different positive tone photoresists without freezing process. The resist for 2nd
lithography contains a specific solvent to prevent the mixing of two resists and there is an activation energy gap
between 1st and 2nd resists to maintain 1st lithography pattern. The double patterning can be successfully processed by
these specific resists without freezing process.
In this study, the performance of this freezing free "Posi/Posi" process is investigated for pitch splitting pattern using
1.35 NA exposure tool. The imaging results including CD control capability, and etching results are collected for 32nm
half pitch and below. Additionally the two-dimensional pattern imaging is also obtained for 76nm minimum pitch.
We report the development and applications of ArF negative tone resist for ArF immersion lithography. New developed
topcoat-free ArF negative tone resists has sufficient water repellent capability that is applicable to over 700mm/s scan
speed water immersion exposure tool and suitable leaching suppression capability within reaching specification of
exposure tool. We demonstrated lithographic performance of topcoat-free negative tone resist utilizing 1.07NA
immersion tool and confirmed the lithographic window of 55nm 1L1S and 50nm 1L1S. And 27.4nm of isolated space
pattern at over dose condition of 55nm 1L1S patterning. This result shows the possibility of topcoat free negative tone
resist for dual trench based litho-etch-litho-etch double patterning. Additionally we have demonstrated contact hole
patterning utilizing double exposure and generated 65nm gridded contact hole patterns utilizing 0.92NA ArF scanner
with applicable pattern profiles.
Double patterning with 193nm immersion lithography is generally recognized as a candidate for 32nm hp node and
possibly beyond with recent progress. LLE (Litho-Litho-Etch) could be good candidate for double patterning method
because of its simplicity but the good solution hasn't been proposed yet.
In last year, freezing free Posi/Nega process was introduced as candidate for LLE process. But that had an issue that the
resolution of negative tone resist was little bit poor for 1L/3S pattern compared with positive tone. Thus it's better to
choose positive tone as 2nd resist for this reason. And then Posi/Posi process without any freezing material has been
investigated and successfully established to image double patterning.
Posi/Posi process without any freezing material has successfully achieved to image below 32nm hp. Furthermore contact
hole imaging was succeeded by using cross-line method and image reverse method.
We present the productivity study of freezing free Posi/Posi process on Cross-lined contact hole, critical resolution for
pitch splitting and reverse imaging for contact hole.
Double patterning based on existing ArF immersion lithography is considered the most viable option for 32nm and below CMOS node. Most of double patterning approaches previously described require intermediate process steps like as hard mask etching, spacer material deposition, and resist freezing. These additional steps can significantly add to the cost of production applied the double patterning. In this paper, pattern freezing free litho-litho-etch double patterning process is investigated to achieve a narrow pitch imaging without the intermediate processing steps. Pattern freezing free litho-litho-etch double patterning utilizing positive-positive resist combination demonstrated composite pattern generation.
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